The present disclosure relates generally to medical devices and, more particularly, to the use of continuous wave photoacoustic spectroscopy and other medical monitoring data to help distinguish sepsis from shock.
This section is intended to introduce the reader to aspects of the art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the field of medicine, doctors often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of devices have been developed for monitoring many such characteristics of a patient. Such devices provide doctors and other healthcare personnel with the information they need to provide the best possible healthcare for their patients. As a result, such monitoring devices have become an indispensable part of modern medicine.
For example, clinicians may wish to monitor a patient's blood flow and blood oxygen saturation to assess cardiac function. Deviation from normal or expected values may alert a clinician to the presence of a particular clinical condition. A patient's microcirculatory system, which includes the arterioles and capillaries, is involved in delivering blood to various organs. A change in blood delivery to these organs may be an indication of injury or disease. By monitoring changes in microcirculation, a clinician may be able to diagnose or monitor diseases in particular organs or tissues. In addition, changes in microcirculation may predict systemic changes that present earlier or more profound microcirculatory changes, followed by changes in blood flow to larger vessels. For example, in cases of shock or pathogenic infection, a clinical response may include shunting of blood from the microcirculatory system to the larger vessels in an attempt to increase blood flow and prevent injury to primary organs (e.g., the brain and heart) while temporarily decreasing blood flow to secondary organs (e.g., the gastrointestinal system or the skin).
Changes in microcirculation may be monitored by techniques for assessing blood volume. Some techniques may be invasive and involve the use of radioisotopes or other tagged blood indicators. The indicators may be tracked through the circulation to estimate the blood volume. Many of these techniques involve indirect assessment of blood volume by measuring the density or concentration of certain blood constituents. For example, sound velocity measurements may be used for measuring several hemodynamic parameters. However, such sensors utilize a linear approximation of a non-linear relationship between the sound velocity and the density of the blood. This approximation may limit the accuracy of the technique. In addition, these techniques may not be suitable for assessing local changes in microcirculation.